Conventionally, a guide lamp has been used to guide people to an evacuation route in case of emergency such as fire or the like.
FIG. 8 is a schematic diagram of a conventional guide lamp 8 including a light transmitting case 81 formed of a synthetic resin such as an acrylic resin or the like and a fluorescence lamp 82 provided in the case 81. The case 81 has a mark showing a running person in two colors, e.g., green and white, and the fluorescence lamp 82 is connected to a lighting circuit connected to an AC power source.
The power of the AC power source may be interrupted in an emergency, so that an emergency power supply using a storage battery is connected to a lighting circuit. A current is constantly supplied to and stored in the emergency power supply in a normal case, and the emergency power supply supplies power to the lighting circuit when the power of the AC power source is interrupted in an emergency. However, the conventional guide lamp 8 is disadvantageous in that the fluorescence lamp 82 has a short life span and cannot be turned on for a long period of time due to rapid power consumption of the emergency power supply in an emergency.
Accordingly, there has been recently proposed a thin-type and long-life organic EL guide lamp 9 in which a planar light emitting element 92 is used as a backlight of a guide lamp panel 91 as shown in FIG. 9 (e.g., Japanese Patent Laid-open Publication No. 2008-165337).
In this organic EL device guide lamp 9, in order to avoid the problem that it is difficult to light for a logn period of time due to rapid power consumption of the emergency power supply in an emergency such as power failure or the like, the power consumption of the emergency power supply is reduced by decreasing brightness in the emergency by reducing a current flowing in an organic EL element as a light emitting element.
However, the conventional organic EL element guide lamp 9 is disadvantageous in that a sufficient lighting period of the guide lamp cannot be ensured due to deterioration of the emergency power supply in the emergency.
Moreover, in the conventional guide lamp, the mark showing a running person in two colors of green and white is provided at a translucent panel made of a synthetic resin, so that a contrast ratio between green and white is determined by transmissivity of the panel. Therefore, it is difficult to save the power by using the contrast ratio between green light and white light, for example.